Well treatment process

Abstract

Hydroxyacetic acid condensation product is used as a fluid loss material in a well completion or workover process in which a fluid comprising a hydrolyzable aqueous gel is used. The hydroxyacetic acid condensation product degrades at formation conditions to provide hydroxyacetic acid which breaks the aqueous gel, thereby restoring full formation permeability without the need for separate addition of gel breaker.

We claim: 
     
       1. In a process for treating a well in a subterranean formation penetrated by a wellbore wherein a well treatment fluid comprising an aqueous gel is pumped down said wellbore as part of a well treatment procedure, wherein a particulate fluid loss additive is included in said well treatment fluid, and wherein a gel filter cake is formed on the surfaces of said wellbore in said formation, the improvement comprising: utilizing as at least a part of said fluid loss additive a hydroxyacetic acid condensation product, said condensation product being degradable at formation conditions whereby hydroxyacetic acid monomers and dimers are formed, and said condensation product being present in an amount sufficient to provide enough degradation products including hydroxyacetic acid to react with and break the gel in said filter cake and to recover permeability in said formation without the necessity of adding a separate gel-breaking material after formation of said gel filter cake.   
     
     
       2. The process of claim 1 wherein said gel is hydroxyethyl cellulose. 
     
     
       3. The process of claim 1 wherein said hydroxy-acetic acid condensation product is a condensation product of hydroxyacetic acid with up to 15 weight percent co-condensing compounds containing other hydroxy-, carboxylic-acid-, or hydroxycarboxylic acid moieties, said condensation product having a number average molecular weight of about 200 to 4000, being substantially crystalline at both ambient and wellbore temperatures and having a melting point of about 160° C. or higher and sufficiently high to avoid softening or melting during use and being substantially insoluble in said treatment fluid and degradable in the presence of water at elevated temperature to monomers and dimers which are at least partially soluble in oil or water. 
     
     
       4. The process of claim 3 wherein said aqueous gel is fully hydrated prior to being combined with said condensation product. 
     
     
       5. The process of claim 4 wherein said fluid loss additive consists essentially of said condensation product. 
     
     
       6. The process of claim 4 wherein said condensation product is added in an amount of at least 10 pounds per 1000 gallons of treatment fluid. 
     
     
       7. The process of claim 6 wherein the average particle size of said condensation product is from 10 to 50 microns.